Hi, Sorry for the rather long, boring post.

In another post, I am helping a friend, install his new sidecar. He, like many new sidecar owners are in total joy and some bewilderment all at the same time. Sidecars are indeed different. Ok, sidecar people may also be indeed different. He is not a huge guy, and is a little surprised by, among other attributes operating a sidecar rig...."Low Speed Wobble"

So, in an effort to explain what it is, and why it happens, I set off writing down what I think I know. So, what I think I know, may not be what is accurate.

Why I posted, and what I am asking, is for some of you real experts (smitty901 and others) to help me/us define some of these sidecar attributes one at a time. who knows, maybe in the end, we will produce the latest, most modern sidecar documentation. Tell me if you agree or where you disagree, and why.

Thanks

Here we go...........................

I was thinking….about “Low speed Wobble”

Based on my own personal experiences, and a lot of research, I have written, what I think is an accurate description of effect.

What this is NOT about: Sidecars turning right or left, only moving straight ahead.

First: “Low speed wobble” is a real, and an inherent fact of traditional sidecar operation. They ALL “wobble.” All that can be achieved is minimizing “wobble,” not elimination.

“Steering Damper – Does NOT eliminate “wobble” a steering damper reduces the felt effects of “wobble” to the rider. (The pressures that cause and create the front handlebar movement are still in affect).

So to Minimize “wobble.”

I think it would be helpful to relate sidecar adjustments and possible causes directly and only to “wobble.” I am trying to eliminate all possibilities that do not relate!

A USA right mounted sidecar has only 3 possible conditions it might be operated under….

1. Going straight down the road
2. Turning right
3. Turning left

Consider the issue of what we call “wobble”

· What is Wobble? Wobble is the minute right to left movement of the handlebars at low speeds that goes away as speed increases and returns at a predictable speed upon de-acceleration.

· Wobble is ONLY present while going straight down the road (condition 1 above) and is felt at a predictable speed.

What factors relate directly to “Wobble?”

1. Factors related to the sidecar
2. Factors related to the motorcycle.



Sidecar Factors:

1. Weight of the sidecar*
2. Length of the sidecar
3. Width of the sidecar
4. Sidecar adjustments*
a. Track
b. Lead
c. Toe-in*
d. Bike Lean out*

* Factors that might influence “Wobble.”

When considering operating the sidecar straight (without turning) I don’t think any relationship exists regarding sidecar length or width, of the sidecar. The weight of a sidecar might have some relation based on, assisting the wobble to be amplified by increased mass pushing on the bike.

Track would not influence “Wobble.” A track of 6 feet wide should go down the road just as straight as a track of 12” wide

Lead would not influence “Wobble.” A lead of 6 feet should glide straight down the road just as well as a lead of zero, (like some some older Harley rigs).

I believe that toe-in, and bike lean out, do influence “wobble” As the motorcycle wheels drive forward, the sidecar wheel try’s to push the motorcycle wheel at an angle. (due to toe-in, and bike lean out) The rear motorcycle wheel is fixed (within the swing arm). The front motorcycle wheel is fixed as best possible in the grip of the riders hands and arms. I believe it is this struggle that creates “wobble.” This would also validate why two different people can ride the same rig and have different opinions about how bad, or good, the “wobble” appears to be. The crown of different roads might also have some relevance.

Motorcycle Factors:

1. Weight of the Motorcycle
2. Wheel base
3. Fork Rake
4. Tire Diameter
5. Mechanical Integrity/Condition
a. Steering Head Bearings*
b. Swing Arm Bearings*
c. Tire Pressure*
d. Shock Stiffness*

* Factors that might influence “Wobble.”

When considering operating the sidecar straight (without turning) I don’t think any relationship exists to Motorcycle weight, wheel base, Rake, or tire diameter. I do however feel that the mechanical integrity of the steering bearings, swing arm bearings, tire pressure, and shock stiffness, are directly related.

Conclusion: Sidecar low speed wobble is an inherent factor of operation. The wobble is created by the need for sidecar toe-in adjustment, and bike lean-out adjustment, to facilitate sidecar operations in turns. Low speed wobble can not be eliminated but it can be minimized. To reduce low speed wobble, one should concentrate on ensuring proper steering head bearing adjustment, tire pressure adjustment, condition of the swing arm bearings, stiff shocks, and proper sidecar toe-in bike lean-out. A steering damper should only be considered after all adjustments and maintenance checks are verified.

 

Yes some low speed wobble or shaking is considered normal , it does not mean you can not get rid of it. Often all that is need is a steering dampener , installed in the right place. It is not dangerous ,but is alarming to the new sidecar rider.
Steering dampener is part of a completed install . Yes you can get away without one . But like most short cuts not worth leaving it off.
The reason two or more may feel it at different speeds is related to weight, and how they sit on the bike most often. How they grip the bars will effect it also. The condition of the road will set the shake in motion and your reactions will either mitigated it or increase it.
If the road has a high crown and is rough shape it is more likely to set it in motion. Another useful tool in working with handling issues is the ECC. Once you try one you will understand. Older ones were manual and kind of a pain to use. ECC work well older ones could be jerky when operated. The new ones like on my Hannigan are smooth to operate.
The statement it can not be eliminated is not correct it can. It may be more involved on some rigs than others This one has no shake or wobble at any speed on any road. It is stable at 5 mph or 110 Mph. Empty or loaded. However no short cuts taken it was done right and no expense was spared. The black one Street is a budget one no dampener yet as an experiment no ECC . It does experience a slight shake/wobble at very low speed. The Fatboy had some until the dampener was installed

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